1. Field of the Invention
The present invention relates to a vehicle control system which automatically shifts to an appropriate driving mode in the case where an abnormality occurs in an onboard control device.
2. Description of the Related Art
Generally, when an abnormality occurs in the control device, an onboard control device disables additional function of the control device while maintaining the basic function related to driving performance is maintained, compensate the vehicle performance using other remaining systems. As an example of the former, Japanese Unexamined Patent Application Publication (JP-A) No. 2011-99394 discloses a technology which sets a first driving power as a target driving power in a vehicle driving power control device when the vehicle driving power control device is in a failed state, the vehicle driving power control device including a driving power calculation unit configured to calculate a first driving power based on the related characteristics between an accelerator opening and the driving power of a driving power source, and to calculate a second driving power using the first driving power as a reference value, the second driving power decreasing gradually with an increase in elapsed time. As an example of the latter, Japanese Unexamined Patent Application Publication (JP-A) No. 2006-282036 discloses a technology which improves a roll restraining effect by increasing the stiffness of a stabilizer bar in the case where the roll restraining effect by a vehicle height adjustment device reduces in a vehicle suspension system including a roll restraining device which restrains the roll of the vehicle body.
Like the example of technology disclosed in the above-mentioned JP-A Nos. 2011-99394 and 2006-282036, when a warning light lights up due to an occurrence of an abnormality in a control device, a driver can recognize which control device has an abnormality, and attention to the driver is drawn. However, it is difficult for the driver to appropriately and immediately understand what operation should be done specifically for driving the vehicle until the control device having an abnormality is repaired. For example, in the case where an output is reduced due to an engine malfunction, the driving speed also decreases, however, the driver usually does not come up with the idea that a sufficient inter-vehicle distance should be taken in order to avoid unnecessary acceleration and deceleration. Thus it is difficult for the driver to take appropriate action except for repairing the vehicle quickly, and therefore, a solution for improving the safety of vehicle has been demanded.